Field of the Invention
The present invention relates to a bus bar module, or more specifically, to a structure for engagement between resin bus bar cases which house bus bars for connecting multiple battery cells in series and resin covers which cover openings of the bus bar cases.
Background Art
A battery pack (also referred to as an assembled battery or a battery unit) formed by connecting multiple battery cells in series is used as a direct-current power source for driving an electric motor in an electric vehicle, a hybrid car or the like. As described in Japanese Patent Application Publication No. 2011-238544 (Patent Document 1), such a battery pack is fabricated by forming a battery assembly in which positive electrodes and negative electrodes of multiple battery cells alternately arranged side by side are bundled and the positive electrodes and the negative electrodes of the adjacent battery cells are connected in series by using conductive bodies called bus bars, and, if necessary, by housing the battery assembly in a housing. Then, the battery pack is put to use.
The bus bars are respectively housed in box-shaped bus bar housing units (hereinafter referred to as bus bar cases) made of an insulative resin. The bus bar cases are connected in an arrangement direction of the battery cells by using U-shaped flexible connecting members. Then, a bus bar module is formed in such a way that: the columnar positive and negative electrodes of the battery cells are inserted into holes formed in the bus bars, and are fixed thereto with nuts or the like; and the bus bars and the electrode members exposed on an opening side of the bus bar cases are protected by being covered with plate-shaped insulating covers In particular, the insulating covers are formed as multiple separate covers each for a plural number of bus bar cases set appropriately in consideration of a dimensional tolerance of the battery unit. The separate insulating covers are connected to one another using flexible connecting members. Moreover, each insulating cover includes a second engagement portion to be engaged with a first engagement portion provided to a given one of the bus bar cases. The bus bar module is formed by engaging the first and second engagement portions (hereinafter referred to as a lock mechanism as appropriate) with one another.